Emergency operating mechanism for dual nozzle oil burners



J. A. LOGAN EMERGENCY OPERATING MECHANISM FOR DUAL NOZZLE OIL BURNERS Filed July 11, 1947 March 15, 1 949.

INVENTOR warp/1A. Lam/v Patented Mar. 15, 1949 EMERGENCY OPERATING' MECHANISM FOR DUAL NOZZLE OIL,

Joseph A. Logan, Hadley, Mus, signer-to Gib.

bert & Barker Manufacturing Company, West Springfield, Mass a corporation of Massachusetts Application July 11, 1947, Serial No. 0,398

8 Claims. ((1158-28) p l I This invention relates to improvements in.oil burners, which are adapted for house heating use and which involve two alternately operable, oilatomizing nozzles.

The provision of two alternately-operable nozzles in the burner may be for any purpose. One example of one advantageous use of the arrangement is to secure two different firing rates. such as a relatively high firing rate for the more severe days of the heating season and a relatively low firing rate for the milder days of the heating season.

The invention has for its object the provision in an oil burner of the class described. of automatic means operable in the event that either one of the nozzles which is selected for operation should become inoperable because of clogging or any other, reason, to connect the other nozzle for operation in its place.

The invention will be disclosed with reference to the accompanying drawing, in which the figure shows diagrammatically an oil burner embodying the invention.

Referring to the drawing, the burner includes two oil-atomizing nozzles l and 2 mounted in a tube 3, near the open and outlet end 4 thereof. The other end of tube 3 is connected to the outlet of a fan housing 5, containing a fan 6, which is driven from an electric motor I by' means of a.

shaft 8. The fan housing 5 has an air inlet 9, controlled by a shutter Ill, mounted on a screw H, by means of which the position of the shutter may be adjusted. The shutter is located inside a casing l2, having air inlets IS. The motor 1 likewise drives an oil pump it for supplying oil to either of the-nozzles i or 2. This pump is operable to draw oil through a suction pipe l5 from a suitable supply tank (not shown) and force the oil outwardly through a pipe IS, a valve casing ll, a pipe l8 and into a casing l9, containing a pressure-regulating valve 20. Valve opens only after the oil has been placed under a predetermined minimum pressure, say for example 1 85 pounds per square inch. When valve 20 opens, oil passes outwardly through a pipe 2i leading.

to branch-pipes 22 and 23, which respectively connect with valve casings 24 and 25. These casings 24 and 25 contain valves 26 and 21, re-

through pipes 88 and ILto the nozzles l and 2, re-

spectively. The solenoids are energized alternately, as will later appear. The oil supplied to the nozzles is held from exceeding a predetermined maximum pressure by means of a by-pass valve 32 in'valve casing ll. Valve'fl opens, when the pumped oil exceeds the predetermined maximum pressure. say Hill pounds per square inch and allows some of the pumped oil to flow back through a by-pass pipe 32' to the suction side of pump H, as to the suction pipe ii. The oil supplied to either nozzle l or 2 is suitably ignited, as by a pair of spark electrodes 33, connected as by a pair of wires 24, to the secondary 35 of a suitable ignition transformer 20.

In the example shown, the nozzle l is intended to supply oil at a relatively low firing rate and the nozzle 2 is'in tended to supply 011 at a relatively high firing rate. The shutter i0 is adjusted, as by turning screw II, to supply air for combustion at the proper ratewhen the low'rate nozzle I is in operation. When the high rate nozzle 2 is in operation, the shutter Ill is opened wider to supply air at the higher rate required.

35 This is effected in the example shown by means of the solenoid 29. which when energized lifts valve 21 by means of-it's plunger 38'-u'ntil the valve abuts 'a shoulder 31 in casing 25 'as' a stop. This plunger is connected'at one end to one end of a lever 38 which is pivoted intermediate its ends andfat the other end is forked to straddle the outerfind of screw l I. A spring 39 tends to move this screw inwardly until a shoulder 40 on the screw abuts the casing l2. The lever 38 is adapted to engage an adjustable abutment, such as a nut ll, on screw II and move the screw axially outa ward carrying the shutter II) to a new position aitording a wider inlet opening. This high firing rate position of the shutter is adjustable by tuming the abutment II on screw i i.

The electric motor 1;, and thus the oil pump N and air fan 6, are started andjstopped under the conventional room-thermostatcontrol. And the-primary .2 of the ignition transformer 38 is adapted to be energized simultaneously with the motor by the same control. The room thermostat switch is indicated at 3 and it is arranged in a low voltage circuit which is supplied from the secondary 44 of a transformer 45. Such circuit may be traced as followsfrom one terminal of secondary by a wire 41 to one terminal of thermostat switch 42 and from the other terminal of such switch by a wire 46 to one terminal of the coil 42 oi. a relay and from-the other terminal of coil 48 by a wire 48' to the other terminal of secondary 44. The primary 49 of transformer 45 is connected by'wires 58 and to terminals 52 and 58, respectively, which are adapted for connection to supply wires 54 and 55, respectively.

On a demand for heat from the burner, the room thermostat switch 88 will close and cause coil 88 to be energized. This results in the ciosing of a switch 55, which closes acircuit to the motor l and ignition transformer 38. This latter circuit includes a wire 5?, connecting terminal 58 and thus supply wire 58 to one terminal of switch 55; a wire 58, connecting the other terminal of switch 55 to one terminal of a safety switch 58; a wire 58, connecting the other termireel of switch 58 to a terminal 8!; a wire 62, connecting terminal 8i to one terminal of motor '5; and a wire 83, connecting the other terminal of the motor l to terminal 58 and supply wire 55. The primary 82 of the ignition transformer 88 is connected by wires 58 and 85 to wires 82 and 68, respectively, and thus in parallel with motor '8. Thus, when switch 56 closes, the motor I will be started to drive the fan 8 and pump l4 and the transformer 38 will be energized to supply ignition for the burner.

The switch 59 is the usual combustion safety control arranged to stop the burner if combustion does not occur within a short predetermined time, say 60 seconds. Switch 59 may be assumed to be a spring blade, having a tendency to swing to the left into open position but being normally restrained from so doing by the bi-metallic thermostat 86. The latter is heated by an electric heating coil 87 and if this heating is continued for the predetermined time interval, the thermostat 88 will bend downwardly enough to release switch 59 and allow it to open. The switch is of the type that will remain open until manually reset, as by a push button 88. One terminal of the coil Bl is connected by a wire 88 to terminal 58. The other terminal of this coil is connected by a wire l8'to one terminal of a switch ii and the other terminal of this switch is connected by a wire 72 to the terminal 8i. Thus, the coil is energized through a circuit, which may be traced as follows-from supply wire 54, terminal 52, wire 5!, switch 58, wire 58, switch 59, wire 88, terminal 8i, wire i2, switch ill, wire it, coil 81], wire 89, terminal 53 to supply wire 55. Switch ii is actuated by a combustion responsive element, such for example as a stack thermostat it, which opens switch '6 i, when combustion ocours, and disconnects the electric heating coil from its supply circuit. If combustion does not occur within the predetermined time interval, switch 59 will open and stop the burner.

The solenoids 28 and 29 which actuate the firing rate selector valves 28 and Z1, respectively, may be controlled in any suitable way and manually or automatically, as desired. A: one illustrative example, I show a thermostat 14, which responds to outdoor temperature and operates to tilt the tube 15 of a mercury switch from one to the other of two extreme positions. The switch 15 is an automatically operable selector switch. If for example the outdoor temperature is below 20 Fahr., the tube will occupy the illustrated position and the wires I8 and TI will then be electrically connected. If, however, the outdoor temperature is above 20 Fahr., the tube I5 will occupy a position at right angles to that shown, so that the mercury in the tube will electrically connect the wires 18 and 18. The switch 15 might equally well be worked by hand where the automatic operation is not necessary or desired. The

' nected by a wire 89 to wire 82.

I other nozzle.

wire I8 is connected to terminal 8! and thus, through the safety switch 59 and relay switch 58. to supply wire 54. Wire 'I'l extends to one terminal of a time switch I9, the other terminal of which is connected by a wire 89 to one terminal of solenoid 29. Wire 18 extends to one terminal of a time switch 8|. the other terminal of which is connected bya wire 82 to one terminal of solenoid 28. The other terminals of solenoids 28 and 29 are connected together by a wire 83, which is connected by a wire 84 to the terminal 83. These two solenoids are thus located one in each of two control circuits and the selector switch is adapted to connect either control circuit to a source of power. With the switch 35 positioned as shown, when the switch 56 closes on a demand for heat from the burner, the solenoid 89 will be energized to open oil valve 8! and allow oil to flow to nozzle 2 for firing at the high rate. At the same time the shutter 18 will be moved to its proper position for high rate firing. The control circuit to solenoid 28 may be traced as followsfrom supply wire 54, terminal 52, wire 51, switch 58, wire 58, switch 58, wire 59, terminal 6|, wire 16, switch 15, wire 11, switch 19, wire 88, solenoid 29, wires 83 and 84, terminal 53 to supply wire 58. Should the temperature rise above .the predetermined rate for which thermostat I4 is set, then the switch 15 will be actuated to connect wires 16 and 18. On a demand for heat from the bumer, the solenoid 28 will then be energized to open valve 28 and allow oil to flow to the nozzle I for low rate firing. The valve 21 will be closed and the shutter 18 will have been moved back into the illustrated position. The control circuit to solenoid 28 may be traced as follows-from supply wire 54, terminal 52, wire 51, switch 58, wire 58, switch 59, wire 69, terminal 6|, wire 15, switch 15, wire l8, switch 8|, wire 82, solenoid 28, wires 83 and 84, terminal 53 to supply wire 55. A,

In a burner of the general kind described. where there are two oil atomizing nozzles which are alternately operable, this invention provides means for continuing the burner in operation, should one nozzle fail, by changing over to the Each nozzle, insofar as this invention is concerned, serves as a spare nozzle available for use in an emergency on failure of the other nozzle. The time switches 19 and 8i form part of the change over means for the purpose described. Each of these switches is or may be like the switch 59. There are bi-metallic thermostats 85 and 86 for normally holding the switches 19 and 8i, respectively, in their illustrated positions and electric heating coils 81 and 88 for heating the thermostats 85 and 86, respectively. Each of these heating coils is designed to heat its thermostat sufliciently to release the switch held by the thermostat in a shorter interval than that required in the case of switch 58. say for example 30 seconds. On release of switch 19, it will become disconnected from the contact, which is connected to the wire 88, and will thus break the control circuit theretofore existing to solenoid 29. Shortly after this circuit is broken, the switch 19 will engage a contact which is con- An emergency circuit will then be closed to the solenoid 28, which circuit may be traced as follows-from supply wir 54, terminal 52, wire 51, switch 58, wire 58, switch 59, wire 88, terminal 5|, wire 18, switch 15, wire 11, switch 19, wires 88 and 82, solenoid 28, wires 83 and 84, terminal 58, to supply wire 55. Assume now that selector switch II is in its other position, so that solenoid 28 will be .which circuit may be traced as followsfrom supply wire 54, terminal 52, wire 51, switch 58, wire 58, switch 59, wire 89,, terminal 8|, wire 18, switch 15. wire 18, switch 8|, wires 99 and 89, solenoid 29, wires 83 and 84, terminal 53, to supply wire 55. Thus, when either of these switches 19 or 8| is released from its normal position, it

will connect to a source of power an emergency circuit which includes the solenoid that is normally controlled by the other of these switches.

The release of the time switches 19 and 8| is eifected by failure of combustion. The heating coils 81 and 88 are located in energizing circuits, which will be closed until combustion occurs, when they will be opened by a suitable combustion responsive device, which may for example be the stack thermostat 13. As shown this thermostat actuates two other control switches 9| and 92, opening them, when combustion occurs at the burner, and maintaining them closed, when there is no combustion at the burner. Switch 9| has one terminal connected by a wire 93 to wire 11 and the other terminal is connected by a wire 94 to one terminal of coil 81. The other terminal of the coil 81 is connected by a wire 95 to a. wire 98 and the latter by a wire 91 to terminal 53.

The switch 92 has one contact connected by a wire 98 to wire 18 and the other contact is connected by a wire I99 to one terminal of coil 88. The other terminal of the coil 88 is connected byawireI9I towire 91.

Assuming that a demand for heat occurs and that selector switch 15 is in its illustrated and high-firing rate position, an energizing circuit will be closed to heating coil 81, as followsfrom supply wire 54, terminal 52, wire 51, switch 59, wire 58, switch 59, wire 69, terminal 6|, wire 16, switch 15, wire 11 as far as wire 93, wire 93, switch 9|, wire 94, coil 81, wires 95, 95 and 91, terminal 53 to supply wire 55. Thus, coil 81 will be heated until combustion occurs, when switch 9| will open to disconnect this coil. If combustion does not occur within the predetermined time, time switch I9 will be released to close its emergency circuit and cause solenoid 28 to be energized and the low firing rate nozzle I brought into action in place of the high firing rate nozzle 2.

Now, if the selector switch 15 is set so that solenoid 28 is energized to bring nozzle I into action, and a demand for heat occurs, an energizing circuit will be closed to the heating coil 88.

Such circuit may be traced as followsfrom sup-- ply wire 54, terminal 52, wire 51, switch 56, wire 58, switch 59, wire89, terminal 6|, wire 15, switch 15, wire 18 as far as wire 98, wire 98, switch 92, wire I99, coil 88,=wires |9I and 91, terminal 53 to supply wire 55. Thus coil 88 will be heated until combustion occurs, when switch 92 will open and disconnect the coil. If combustion does not occur within the predetermined time, switch 8| will be released to close its emergency circuit and cause solenoid 29 to be energized and the high firing rate nozzle 2' brought into play in place of the low firing rate nozzle I.

Whenever the time switch 19 or 8| is released by operation of the bi-metallic thermostat 85 or 88, respectively, it cannot be restored to normal position except by manual resetting. And, when either such switch is released, it is because an abnormal condition exists, such as requires a service man. It is desirable, therefore, to give some indication that such an abnormal condition exists. For this purpose, each switch is made to operate a suitable indicator which may be of any suitable type. As herein exemplified, the indicators for the switches 19 and 8| are electric lamps I92 and I93, respectively. The lamp I92 is connected by a wire I94 to a contact of the switch 19 and by a wire I to the wire 95. The lamp I93 is connected by a Wire I99 to a contact of the switch 8| and by a wire I91 to wire I95. When the time switch 19 is released, as heretofore described, it will engage the contact, to which wire I94 is connected, and close a signal circuit to lamp I92. Such signal circuit may be traced as followsfrom supply wire 54, terminal 52, wire 51, switch 55, wire 58, switch 59, wire 99, terminal 6|, wire 15, switch 15, wire 11, switch 19 wire I94, lamp I92, wires I95, 96 and 91, terminal 53 to supply wire 55. When the time switch 8| is released, a signal circuit will be closed to lamp I93. This circuit may be traced as follows, from supply wire 54, terminal 52, wire 51, switch 59, wire 58, switch 59, wire 69, terminal 9|, wire 16, switch 15, wire 18, switch 8|, wire I99, lamp I93, wires I91, I95, 95 and 91, terminal 53 to supply wire 55. Thus, when either time switch 19 or 8| is released a signal will be given to indicate the inoperativeness of nozzle 2 or I, respectively, and such signal will remain on, as long as the burner is in operation, until its switch is manually reset. Should it be desired to maintain the signals on while the burner is not in operation, the switches 19 and 8| can be made to connect their respective wires I94 and I95 directly to the supply wire 54 and thus by-pass the relay switch 59 and combustion safety switch 59.

The invention is not concerned with the structural details of the burner and therefore the illustration has been confined to a diagrammatical showing of the essential elements and their operative relationship. The burner may be of any suitable type and as an example of one suitable type reference is made to my prior Patent No. 1,985,934, granted January 1, 1935. It is contemplated that the invention will be used with allthe various safety devices and the various accessories customarily used with burners of this type. Such controls as have been illustrated have been shown merely schematically to indicate their functions.

The operation of the burner will be summarized. On a demand for heat from the burner, as evidenced by the closing of the room thermostat switch 43, the relay switch 55 will close a circuit to the motor 1, causing the latter to start and drive the air fan 6 and oil pump I4. At the same time the ignition transformer will be energized to supply electricity to the ignition electrodes 33 As the motor circuit is closed, the selection of the firing rate will be made. The outdoor thermostat switch 15, or a hand-operated switch or any other switch that may be used in its place, merely preselects the solenoid 28 or 28, which will be' energized when the relay switch 56 is closed. If the switch 15 is set, as shown, to select the solenoid 29, the latter will be energized, when the motor circuit closes, in order to open valve 21 and allow oil to flow to nozzle 2. The switch 15 also selects a timing mechanism for 30 seconds unless combustion occurs before the end of this time interval. Should this nozzle 2 be inoperative, for any reason, as for example because it is plugged up with carbon, then no oil will issue from the nozzle and in 30 seconds, the coil 81 will have heated thermostat 85 sufilciently to release switch 19 and allow it to connect with wire 89, whereby the control circuit to solenoid 29 will be opened and-the emergency circuit to solenoid 28 will be closed. Thus, the valve 2'! will first be closed and then valve 28 will be'opened to allow oil to fiow to the nozzle i. If this nozzle l is operative, the burner will operate and the stack thermostat 13 will in a short time open the switches 1|, 9| and 92, and thus disconnect the heating coils 61 and 81. The coil 88 is already disconnected by switch i5. The lamp I02 will be lighted to show that the nozzle 2 is not in working order. Oil will be supplied from nozzle l in atomized form to mix with the air supplied by fan 6 and the combustible mixture will be ignited by a spark from electrodes 33. The burner will operate but at a lower rate than intended but it serves in an emergency to supply heat.- The burner will continue in operation until the demand for heat is satisfied and room thermostat switch 43 opens to stop the burner, except in the case of failure of combustion. In this case, stack thermostat 13 will close the switches II, SI and 92, and energize the heating coils 51 and 81. The switch 59 will be released in say 60 seconds to stop motor I and shut down the burner. The switches 59 and 19 must be reset before the burner can again operate in the intended manner.

In the event that the switch i is set to select the solenoid 2B, the latter will be energized, when the motor I is started on a demand for heat from a the burner, and valve 25 will be opened to supply oil at a low rate to nozzle I. Should this nozzle I be inoperative, no combustion will occur and the stack thermostat 13 will not open the several switches Ii, 9i and 92 and the coils 6! and 88 will start heating their respective thermostats 56 and 36. The thermostat 86 will operate in 30 seconds and before the thermostat 56 can operate,

to release switch 8! and first open the control circuit to solenoid 28 and thereafter connect with wire til to close the emergency circuit to the solenoid 29, whereby valve 2'! will be opened to allow oil to fiow to nozzle 2. The signal lamp 508 will be lighted to indicate the inoperativeness of nozzle i. When the demand for heat is satisfied, switch 63 will open and stop the burner. Should combustion fail before the demand for heat is satisfied, switch 59 will open and stop the burner. If when the change is made to nozzle 2, the latter is also inoperative, the

.- burner will be stopped by safety switch 59 in the usual way, as above described.

The invention thus provides automatic means, which are operable on the failure of one of two oil atomizing nozzles of the burner to change to the other nozzle and enable the burner to continue to supply heat. At the same time a signalis actuated to indicate the inoper-ativeness of the first-named nozzle. While the invention finds one advantageous use in a burner having two nozzles which are alternately operable and have different firing rates, it may equally well be used where the firing rates of the nozzles are the same, because the invention simply requires that .on the first-named conduit.

aces-goo 8 either of two nozzles may serve as a spare to the other to enable burner operation to be continued in the emergency caused by the failure of one nozzle.

I claim:

1. In an oil burner, comprising in combination, a motor, an air fan, an oil pump, a transmission for driving the fan and pump from the motor, an air conduit connected to receive air from the fan, two oil conduits adapted to receive oil from said pump and each provided with an individual atomizing nozzle located in said air conduit, valve,

means operable to connect either one of said oil conduits to the pressure side of "said pump, control means for starting the motor on a demand for heat and for stopping the motor when such demand is satisfied, means operable when either oil-conduit is co'nnectedto the pump and its nozzle fails to deliver adequate oil for combustion after the motor'starts, to automatically connect the other oil conduit to the pressure side of said pump, and signaling means operable on failure of either nozzle to indicate the inoperativeness of such nomle.

2. An oil burner, comprising in combination, a motor, an air fan, an oil pump, a transmission for driving the fan and pump from the motor, an air conduit connected to receive air from the fan, two oil conduits adapted to receive oil from said pump and each provided with an individual atomizing nozzle located in said air conduit, valve means movable to connect one or the other of said oil conduits to the pressure side of said pump, control means for starting the motor on a demand for heat and for stopping the motor when such demand is satisfied, and means operable when either oil conduit is connected to the pump and combustion fails to occur within a predetermined time after the motor starts to move the valve means to connect the other oil conduit to the pressure side of said pump.

3. An oil burner, comprising in combination, a motor, an air fan, an oil pump, a transmission for driving the fan and pump from the motor. an air conduit connected to receive air from the fan, two oil conduits adapted to receive oil from said pump and each provided with an individual atomizing nozzle located in said air conduit, valve means movable from one position to another to connect one or the other of said oil conduits to the pressure side of said pump, control means for starting the motor on a demand for heat and for stopping the motor when such demand is satisfied, means operable when either oil conduit is connected to the pump and combustion fails to occur within a predetermined time after the motor starts to move the valve means to its other position and connect the other oil conduit to the pressure side of said pump, and signaling means operable on failure of combustion within a predetermined time after the motor starts to give an indication of the inoperativeness of the nozzle 4} An oil burner, comprising in combination, a motor, an air fan, an oil pump, a transmission for driving theian and pump from the motor, an

. air conduit connected to receive air from the fan, two oil conduits adapted to receive oil from said pump and each provided with an individual atomizing nozzle located in said air conduit, control means operable to start the motor on a demand forheat from the burner and to stop the motor when the demand for the heat is satisfied, valves one for each oil conduit, each valve opening and closing to respectively connect and disconnec't its oil conduit to the pressure side of the pump, a timing mechanism for each valve, selector means for connecting one or the other of said valves to be opened when the motor starts and for connecting the corresponding timing mechanism to be started when the motor starts,

each timing mechanism being operable in a predetermined time to close the valve that was opened in order to disconnect the pump from r the selected oil conduit and to open the other valve in order to connect the other oil conduit tosaid pump, and means responsive to combustion at the burner for stopping the timing mechanism that was started with said motor.

5. In an oil burner of the electrically operated type which includes an air fan mechanism to deliver air, an air tube to receive the air, an oil pump mechanism to deliver oil, a conduit and an atomizing nozzle at its end to receive the oil,

the air tube and oil nozzle adapted to bring the in parallel on the discharge side of the oil pump mechanism conduit for the first nozzle, two valve means, one for each nozzle conduit to put its nomle into or out of operating connection with the pump mechanism, two electromagnetc actuating devices one for each valve means, two control circuits one for each actuating device, and a selector switch to connect one or the other of said control circuits to a source of power to actuate one or the other valve means to put in operation one or the other of said nozzles, a heatcontrolled time switch in each of said control circuits, each time switch. normally positioned to deenergize its control circuit when heated beyond a predetermined time, two emergency circuits one for each time switch and each adapted to be connected by the latter through said selector switch to a source of power, the emergency circuit for each time switch including the electromagnetic valve actuating device normally controlled by the other time switch, each emergency circuit being normally open at its timeswitch, each time switch being movable when heated beyond a predetermined time to close its emergency circuit when it opens its valve control circuit, two electric heating elements one for each time switch, two energizing circuits one for each of said heating elements, said selector switch adapted to connected to a source of power the heating element of that time switch which is in the control circuit connected to a source of power by the selector switch, a control switch in each energizing circuit, and a device responsive to combustion at the burner for actuating said control switches opening them when combustion occurs and closing them in the absence of combustion, said parts being constructed and related in the way pointed out for the purpose of automatically shifting from the operation of one burner nozzle to the other burner nozzle in the emergency that one burner nozzle becomes inoperative, whereby the second burner nozzle will carry on the burner operation and the burner will continue to operate.

,6. In an oil burner, having an air supply fan, an oil supply pump, a motor for driving the fan nd P mp. an air conduit connected to receive air from the fan, two 011 conduits adapted to receive oil from the pump and each provided with an'atomizing nozzle located in said air conduit, control means for starting the motor on a demand for heat and for stopping the motor when the demand for heat is satisfied, and valves one for each oil conduit, each valve opening and closing to connect or disconnect its oil conduit to the pressure side of said pump, electromagnetic means controlling the opening and closing of said valves, circuit connections for the electromagnetic means including a selector switch movable from one position in which the electromagnetic means causes one valve to open and the other to close to another position in which the electromagnetic means causes the first valve to close and the other valve to. open, first and second time switches one or the other of which is connected by said selector switch to start when the motor starts accordingly as the selector switch is set to cause the first or the second valve to open, emergency circuit connections for said electromagnetic means controlled by said time switches, and first time switch operable in a predetermined time after it is started to reverse the circuit connections to the electromagnetic means and cause it to close the first valve and open the second valve, said second time switch operable in a predetermined time after it is started to reverse the circuit connections to the electromagnetic means and cause the second valve to open and the first valve to close, and means responsive to combustion at the selected nozzle to stopthe movement of the selected time switch.

7. In an oil burner, having an air supply fan, an oil supply pump, a motor for driving the fan and pump, an air conduit connected to receive air from the fan, two oil conduits adapted to receive oil from the pump and each provided with an atomizing nozzle located in said air conduit, control means for starting the motor on a demand for heat and for stopping the motor when the demand for heat is satisfied, and valves one for each oil conduit, each valve opening and closing to connect or disconnect its oil conduit to the pressure side ofsaid pump, electromagnetic means controlling the opening and ,closing .of said valves, circuit connections for the electromagnetic means including a selector switch movable from one position in which the electromagnetic means causes one valve to open and the other to close to another position in which the electromagnetic means causes the first valve to close and the other valve to open, first and second heat-actuated time switches, first and second electric heating coils for the first and second time switches respectively; first and second energizing circuits for the first and second coils respectively, the first or the second energizing circuits being closed when the selector switch is moved to respectively cause the first or the second valve to open, each time switch connected in circuit with said electromagnetic means and operable when heated for a predetermined interval to reverse the circuit connections to said electromagnetic means and cause the selected valve to close and the other valve to open, and a switch in each of said energizing circuits operable to open its circuit on occurrence of com- 'bustion.

8. An oil burner, comprising in combination, a motor, an air fan, an oil pump, a transmission for driving the fan and pump from the motor, an air conduit connected to receive air from the fan, two oil conduits adapted to receive oil from said pump and each provided with an individual atomizing nozzle located in said air conduit, valve means operable to connect either one of said 011 conduits to the pressure side of said pump and when thus connecting one oil conduit to the pump to disconnect the other oil conduit from said pump, control means for starting said motor on a demand for heat and for stopping said motor when such demand is satisfied, mechanism operable in a predetermined time after bein: started to'actuate said valve means and reverse the connections of said oil conduits with said pump, whereby the oil conduit previously connected to the. pump will be disconnected therefrom" and the other oil conduit previously disconnected from the pump will be connected thereto, and control means for said mechanism including means responsive to the absence or presence of combustion from whichever nozzle is connected to the pump, for respectively startin: said mechanism, whenever said motor is started or in operation, and for stopping said mechanism when combustion occurs, whereby on failure of one nozzle for said predetermined time to deliver adequate oil for combustion, the other nozzle will be automatically connected to operate Number in its place.

JOSEPH A. LOGAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

